The Collaborative International Dictionary of English v.0.48:

Sierra \Si*er"ra\, n. [Sp., properly, a saw, fr. L. serra a saw.
   See Serrate.]
   A ridge of mountain and craggy rocks, with a serrated or
   irregular outline; as, the Sierra Nevada.
   [1913 Webster]

         The wild sierra overhead.                --Whitter.
   [1913 Webster]

WordNet (r) 3.0 (2006):

sierra
    n 1: a range of mountains (usually with jagged peaks and
         irregular outline)
    2: a Spanish mackerel of western North America [syn: sierra,
       Scomberomorus sierra]

The Free On-line Dictionary of Computing (30 December 2018):

Sierra

    (Or "Sierra On-Line") A computer game
   developer founded in the early 1980s by Ken and Roberta
   Willams in the small mountain town of Oakhurst California.
   Sierra was named after the local mountian range, 15 miles from
   the famous Yosemite National Park.

   In 1997 Sierra was purchased by CUC and its main office is
   now in Seattle, WA, USA.

   Products include Kings Quest, Space Quest, Police Quest, Quest
   for Glory, Robin Hood, Phantasmagoria, Leisure Suit Larry, Eco
   Quest and many more.

   (http://sierra.com /).

   (1997-11-23)


U.S. Gazetteer Counties (2000):

Sierra -- U.S. County in California
   Population (2000):    3555
   Housing Units (2000): 2202
   Land area (2000):     953.381960 sq. miles (2469.247836 sq. km)
   Water area (2000):    8.592233 sq. miles (22.253781 sq. km)
   Total area (2000):    961.974193 sq. miles (2491.501617 sq. km)
   Located within:       California (CA), FIPS 06
   Location:             39.582063 N, 120.534038 W
   Headwords:
    Sierra
    Sierra, CA
    Sierra County
    Sierra County, CA


U.S. Gazetteer Counties (2000):

Sierra -- U.S. County in New Mexico
   Population (2000):    13270
   Housing Units (2000): 8727
   Land area (2000):     4180.232226 sq. miles (10826.751302 sq. km)
   Water area (2000):    56.070649 sq. miles (145.222307 sq. km)
   Total area (2000):    4236.302875 sq. miles (10971.973609 sq. km)
   Located within:       New Mexico (NM), FIPS 35
   Location:             33.095349 N, 107.291198 W
   Headwords:
    Sierra
    Sierra, NM
    Sierra County
    Sierra County, NM